A composting apparatus of this kinds is previously illustrated in the published EP patent application 210 382 and in U.S. Pat. No. 3,966,415. Disadvantages of constructions according to these publications are among other things, the their use in winter, when availability of refuse other than household refuse is decreased is very difficult, because the drum includes just one single department and the drum walls are air penetrable in a remarkable extent, therefore there is inside the drum an unnecessary large air space and an unnecessary high air ventilation, which in a combination tend to decrease the internal temperature of the apparatus, whereby there is a risk of total standstill of the composting process.